A TCP (transmission control protocol)/IP (internet protocol) communication scheme is a representative communication protocol used on the Internet. In the TCP/IP communication scheme, a transmitting terminal decides a communication rate to adapt to a communication speed at which communication is performed using a maximum transmittable data size within a range of a window size (information such as the number of data segments or a data size receivable by a receiving terminal) notified from a receiving terminal, and performs communication. It is known that a communication rate to be decided by a transmitting terminal decreases in inverse proportion to a network delay and a square root of a packet loss rate. In other words, in a network having a large delay or a network having a high packet loss rate, the TCP provides poor communication performance.
There is a communication scheme in which data is transferred to a device of a final destination such that data is sequentially transferred between terminals or nodes by using TCP communication as illustrated in FIG. 1. In the communication scheme in which each of a plurality of nodes on a network performs control of deciding a TCP communication rate, a network delay and packet loss are dispersed into network sections between nodes. For this reason, a network delay and packet loss in a TCP connection between nodes are reduced, and thus the communication performance by the TCP is improved. A related art intended to improve the performance of ratio communication is disclosed in Patent Document 1.